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Biomedical subjects

G Renard

Publications and source records attributed to G Renard.

At least 55 records · Page 3Linked to original sources
PubMed2002

[Phototherapeutic keratectomy for the treatment of Cogan's microcystic dystrophy].

PURPOSE: This retrospective study was designed to investigate the therapeutic potential of phototherapeutic keratectomy (PTK) for the treatment of map-dot-fingerprint corneal dystrophy (MDFCD). PATIENTS AND METHODS: PTK was performed with the Excimed UV 200 and with the Nidek EC5000 on 38 patients (55 eyes). Mean patient age was 51 years (range, 28-86 years). The mean follow-up period was 19 months (range, 8-54 months). The treatment goal for each patient was to improve vision (17 eyes), to heal recurrent corneal erosions (28 eyes) or both (10 eyes). RESULTS: In 13 of 17 eyes (76.47%) with reduction in visual acuity, best corrected visual acuity (BCVA) improved by two lines or more. In 36 eyes of 38 (94.7%) with recurrent corneal erosions, there was no recurrence during the follow-up period. No decreased BCVA was noted. No recurrence of corneal dystrophic changes was seen in the ablation zone at the final follow-up. The mean hyperopic shift caused by tissue ablation was +O.55+/-1.35 after 1 year. CONCLUSION: Excimer laser PTK is a safe and effective outpatient treatment and should be used as initial treatment for MDFCD.

Corneal Dystrophies, Hereditary↗
PubMed2002

[Nevus mimicking a basal cell carcinoma of the eyelid].

A clinicopathologic case of a 41-year-old female patient exhibited a single cutaneous tumor at the inner part of the free margin of the inferior left eyelid. It was a pink, fleshy, and nodular well-circumscribed exophytic mass with thin vessels on its surface. Experienced already for 20 years, this lesion had been observed 6 years before and has not exhibited much change since then. However, its clinical appearance argued for a possible small basal cell carcinoma, which had grown over the inferior left lachrymal duct. After surgical removal, histopathology showed that the tumor was an amelanotic dermal nevus. No disturbance of lachrymal drainage was observed after surgery. This case shows that nodular amelanotic tumors of the eyelid, even when located on the inner segment of the eyelid, may be a nevus.

Adult↗
PubMed2002

[Followup of chicken pox keratitis. Anatomic-clinical case report].

Chicken pox is a very common infectious disease in children. Its corneal involvement is less serious than with measles, which may lead to blindness in numerous developing countries. However, with occasional cases occur. A case of a 59-year-old male patient whose left cornea was involved during a chicken pox infection at the age of 7 is reported. More recently, the vision of the right eye was normal at 20/20 and reduced to visual perception in the affected left eye. Corneal sensitivity was maintained in the left eye, which, however exhibited a central epithelial defect. A central round opacity of the left corneal stroma was believed to be the scar resulting from a previous disciform keratitis. The left central cornea was thinned and there was neither an anterior chamber flare nor new corneal vessels. This corneal condition required a corneal allograft, performed quickly because of the potential risk of perforation. Histopathological study of the corneal button showed a central corneal thinning with an increase in epithelial thickness. The corneal stroma was disorganized, with irregular collagen bundles. No inflammatory cells could be observed, however. All the histopathological changes observed were those of a corneal scar.

Chickenpox↗
PubMed2002

[Bilateral keratoconus: a case report].

Among corneal dystrophies, the keratoconus is one of the most frequently observed among young adults. A clinico pathological case is reported in a 13-year-old-girl of African origin. The diagnosis of bilateral keratoconus was established based on the obvious changes of the corneal curvature and thickness. After an unsuccessful attempt to improve vision with contact lenses, a keratoplasty was finally performed on one side to remove the pathological cornea. Its histopathological study found the characteristic changes of keratoconus: breaks of Bowman's layer and corneal thinning.

Adolescent↗
PubMed2002

[Inflammation of an ectopic pinguecula].

An 80-year-old male patient experienced recently diagnosed swelling of the limbal conjunctiva. In his clinical history were found cataract surgery on the right eye 3 months before, chronic open angle glaucoma effectively treated by local eye drops, treated systemic hypertension and hypercholesterolemia. On ophthalmic examination, a conjunctival mass was present in the inferior lateral conjunctival quadrant next to the limbus, with numerous vessels visible at its top. Treatment with topical corticosteroids failed to obtain regression, but decreased the local inflammatory signs. The persistence of the mass led to its surgical excision under local anesthesia. Histopathology found a subepithelial accumulation of modified collagen bundles typical of elastotic degeneration. Capillary vessels were seen in the superficial subepithelial area, attesting to the high degree of vascularization observed clinically. The final diagnosis was a pinguecula, which was not exactly located on the horizontal meridian area as it is usual.

Aged↗
PubMed2002

[Episcleral Miragel buckling elements removal. A clinical case-series].

INTRODUCTION: Due to a long-term alteration in their chemical composition, resulting in excessive swelling, Miragel scleral buckles are now commonly removed. The aim of this study was to determine the characteristics and the outcome of patients needing Miragel buckling removal. METHODS: Retrospective analysis between 1997 and 1999 of the charts of patients successfully treated for retinal detachment and in whom a Miragelepiscleral buckle was removed after surgery with a minimal follow-up of 6 months after removal. RESULTS: The study group consisted of 24 eyes of 13 women and 11 men. Their mean age at removal was 47.1+/-18.4 years. The removed buckle was encircling in nine cases (37.5%), circumferential (<180 degrees ) in 11 cases (45.8%) and radial in four cases (16.7%). An exposed buckle was observed in two cases (8.3%). Reasons for removal were excessive swelling of the buckle inducing ocular motility disturbance in 23 cases and infection of an extruded buckle in only one case. The mean time between implantation and removal was 91.9+/-28.7 months (range 20-120). One case of scleral perforation during removal and one case of retinal redetachment were observed. Three cases of persistent ocular motility disturbance after removal were also noted. CONCLUSION: Late swelling of the buckle was the main reason for removal. Patients undergoing Miragel buckling removal should be informed of scleral perforation during removal, retinal redetachment and persistence of ocular motility disturbance as possible complications.

Adolescent↗
PubMed2002

[Actinic keratosis seborrheic wart and nevus: three distinct cutaneous eyelid skin lesions in a single patient].

A 67-year-old woman had three different tumors of the eyelids. The most prominent one was a nevus of the free margin of the inferior left eyelid. The nevus was followed for 18 months without change while two epidermal papillomatous tumors grew and were surgically removed. Histopathology disclosed that one tumor was a seborrheic keratosis and the other was a pre-epitheliomatous keratosis. Histologic evaluation of the margins showed that surgical removal was complete. A regular examination of the scars was recommended to the patient.

Aged↗
PubMed2001

Chemotactic penetration of keratocytes in ePTFE polymer in vitro.

Expanded polytetrafluoroethylene (ePTFE) is used as a support for artificial corneas. Implanted in corneas, most of the time this polymer is colonized by corneal host cells. The absence of colonization often coincides with extrusion of the polymer. Therefore, we decided to introduce keratocytes into ePTFE in vitro before implantation. Because keratocytes do not spontaneously enter ePTFE, we used several chemoattractants, separately and in a mixture, to stimulate the penetration of cultured keratocytes into the polymer. The influence of the passage number on cell penetration was also studied. No significant differences were observed up to the seventh passage, although seventh-passage cells penetrated somewhat more slowly than younger cells. Satisfactory results were obtained with four of the tested chemotactic factors: IL-6, type alpha transforming growth factor (TGF-alpha), platelet derived growth factor isoform BB (PDGF-BB), and fibroblast growth factor-2 (FGF-2). Under our experimental conditions, two to more than six million keratocytes entered the polymer discs with a volume of 706.5 mm(3) in the presence of these four chemoattractants. TGF-alpha was the most efficient and was selected for further in vitro and in vivo studies.

Biocompatible Materials↗
PubMed2001

Effect of hyaluronan on MMP expression and activation.

Matrix metalloproteases (MMPs) play a crucial role in tissue remodelling in a variety of physiological and pathological processes. Hyaluronan is also involved in the same processes. Several cytokines and growth factors are involved in the regulation of the biosynthesis of hyaluronan and also of MMPs. The activity of MMPs has been shown to be regulated at the level of transcription and activation of the zymogen form. In order to explore the possible relationship between matrix components and especially hyaluronan, we studied the effect of hyaluronan on MMP expression (biosynthesis and activation) in the culture of human skin fibroblasts and corneal keratocytes (explant cultures and cell cultures). These cells were shown to exhibit distinct phenotypes as far as matrix biosynthesis is concerned. Using a synthetic substrate N-Suc(ala)3pNA, we measured elastase-type endopeptidase activity produced by fibroblasts and keratocytes and characterized the MMPs by zymography. Hyaluronan added to fibroblast cultures stimulated the membrane-bound elastase-type endopeptidase activity in a dose dependent fashion. Similar results were obtained with keratocyte cultures. In the presence of 1 mg/ml hyaluronan there was an increase in MMP expression and also an activation of latent MMPs both by fibroblasts and keratocytes.

Cells, Cultured↗
PubMed2001

Three-dimensional supramolecular organization of the extracellular matrix in human and rabbit corneal stroma, as revealed by ultrarapid-freezing and deep-etching methods.

The present work was carried out to clarify the three-dimensional fine structure of extracellular matrix in the cornea, using ultrarapid-freezing and deep-etching methods for electron microscopy. Fresh and glutaraldehyde-fixed samples of human and rabbit posterior corneas were ultrarapidly-frozen onto a copper block cooled by liquid helium or liquid nitrogen, freeze-fractured, deeply etched for 8-10 min and rotary replicated with platinum-carbon. Replicas were examined in a transmission electron microscope equipped with a tilting device. Only structures with repeatedly observed, similar architectural profiles free from ice crystal damage, were taken into account. The very recognizable major collagen fibrils revealed 8-10 nm subfibrils running helically along the fibril long axis. The other extracellular matrix components consisted of: (1) 8-12 nm interfibrillar bridging filaments, frequently ornamented with globular domains, joining neighbouring collagen fibrils like steps of a ladder; (2) 10-20 nm filaments with relatively large globular domains, running on the surface of collagen fibrils along their long axes, and projecting finger-like structures into interfibrillar spaces sometimes attaching to adjacent collagen fibrils; (3) 10-15 nm beaded filaments with a periodicity of 75-110 nm, forming extended networks, especially at the interlamellar interfaces; and (4) 8-14 nm straight or sinuous strands consisting of 4-6 nm repeating subunits or modules, forming extended sheets by lateral association at the Descemet's membrane/stroma interface. In the light of the information available from studies on the localization of extracellular matrix components in the cornea, and by reference to the structural models of extracellular matrix molecules and macromolecular assemblies, we have related the deep-etched extracellular matrix structures described above to: (1) proteoglycans; (2) fibril-associated collagens with interrupted triple helices or FACIT collagens; (3) type VI collagen; and (4) fibronectin, respectively.

Animals↗
PubMed2001

Adventitial sheathotomy for decompression of recent onset branch retinal vein occlusion.

UNLABELLED: Interesting results have been reported on the use of pars plana vitrectomy with adventitial sheathotomy for the decompression of branch retinal vein occlusions (BRVO). Recent onset BRVO responsible for a visual acuity of 20/40 or less have been estimated to be good candidates for this procedure. We report on the results of the prospective evaluation of three eyes (in three patients) with recent onset BRVO which underwent surgical decompression. Three men, aged 40, 50, and 68 years presenting with BRVO for 4, 4, and 3 weeks respectively, underwent surgical decompression. Initial visual acuity was 20/80, 20/80, and 20/200. After 11, 10, and 9 months follow-up, visual acuity was 20/80, 20/200, and 20/200. In two eyes, an increase of the area of retinal non-perfusion was treated with peripheral laser photocoagulation. No cataract, retinal tears or retinal detachment were observed. CONCLUSION: although feasible, sheathotomy did not lead to a significant visual improvement in our patients. Dissection of the arteriovenous crossing could have induced vascular trauma. Furthermore, vitrectomy with posterior hyaloid detachment alone could be of benefit in the treatment of branched retinal vein occlusions. A prospective randomised trial is needed to assess the effectiveness and the safety of this procedure and to determine the best candidates for surgery.

Adult↗
PubMed2001

Silicone punctal plug extrusion resulting from spontaneous dissection of canalicular mucosa: A clinical and histopathologic report.

PURPOSE: To report on an uncommon, previously unidentified, progressive silicone punctal plug extrusion. DESIGN: Small, retrospective case series. PARTICIPANTS: Five cases of punctal plug extrusion were identified among a series of 424 consecutive implantations. Histopathologic analysis was obtained in one case. One additional referred case was included in this report. RESULTS: The plugs were completely extruded from the punctal lumen 6 to 14 months after insertion after an otherwise uncomplicated postoperative course. All plugs were retained at the punctal margin by an encircling band of vascularized mucosal tissue originating from the canalicular lumen. The band consisted of connective tissue of canalicular mucosal origin, attached just below the junction of the punctal and canalicular epithelium. Mild mononuclear infiltration was present in the connective tissue component of the punctal region. There was no cytologic or architectural evidence of abnormal epithelium or connective tissue or of pyogenic granuloma. CONCLUSIONS: These observations suggest that progressive lacrimal punctal plug extrusion may relate to mucosal dissection by the plug edges. We speculate that mechanical stress induced by eyelid closure on an improperly sized or placed implant may result in plug tilt. Subsequent epithelial hyperplasia further enhances the tilt, and the sharper edge of the conical bulb promotes separation of the canalicular mucosa from its distal luminal aspect. At the completion of the extrusion, the mucosal surface is separated from its connective tissue base, at a proximal subpunctal level, causing formation of an encircling tissue band.

Adult↗
PubMed2001

Histologic phenotype-genotype correlation of corneal dystrophies associated with eight distinct mutations in the TGFBI gene.

PURPOSE: To establish a phenotype-genotype correlation of various autosomal-dominant corneal dystrophies among French subjects. DESIGN: Retrospective molecular genetic study and clinicopathologic correlation. PARTICIPANTS: Forty-four subjects from 26 unrelated French families were included in this study, and 60 corneal buttons could be examined at the histologic and ultrastructural levels. METHODS: Light microscopy and transmission electron microscopy were performed on corneal specimens obtained during keratoplasty. Blood samples were collected for DNA analysis. MAIN OUTCOME MEASURES: After genomic DNA extraction from peripheral blood leukocytes of each family member, exons of the TGFBI gene were amplified by polymerase chain reaction (PCR), and the PCR products were directly sequenced on both strands. RESULTS: Four different mutations were found to be responsible for dystrophy of granular type (R555W, R124L, R124H, and R124L+delT125-delE126), three other different mutations produced a lattice type (R124C, H626R, and A546T), and the last mutation identified was associated with the honeycomb-shaped dystrophy (R555Q). Each subtype of dystrophy showed, histologically and ultrastructurally, specific characteristics that are easily recognizable. However, besides these stereotyped forms, differential histologic diagnosis of atypical forms remains difficult, and these forms could be misdiagnosed. CONCLUSIONS: The characteristic biomicroscopic appearance and histopathologic features of each "classic" dystrophy present a significant degree of specificity and generally provide an accurate diagnosis. However, atypical forms in which clinical and histologic data alone could be misleading, are unequivocally diagnosed after DNA analysis.

Cornea↗
PubMed2001

Corneal collagens.

Cornea is a highly differentiated tissue rich in extracellular matrix (ECM) specifically distributed in space in order to insure its dual role--transparency and protection of inner eye-tissues. Corneal ECM is especially rich in collagens. Since the characterisation of a number of distinct collagen types it appeared that most of them are present in the cornea. Their synthesis follows a specific program of sequential expression of the different collagen types to be synthesised during the development and maturation of the cornea. The precise regulation of the diameter and orientation of fibers, and of the interfibrillar spaces is partially at least attributed to interactions between glycosaminoglycans and collagens. The 'program' of vectorial collagen synthesis and GAG-collagen interactions changes also with age and in several pathological conditions as corneal dystrophies and wound healing. The Maillard reaction, especially in diabetes, is one of these important factors involved in age-dependent modifications of corneal structure and function. Far from being inert, corneal collagens were shown to have relatively short half-lives. The biosynthesis of corneal collagens was studied also during wound healing. The refibrillation of wounded corneas does not follow the original 'program' of ECM-synthesis as shown by the comparative study of wound healing using biochemical and morphometric methods. This review recapitulates briefly previous and recent studies on corneal collagens in order to present to clinicians and scientists an overview of the state of the art of this important field at the intersection of eye research and matrix biology.

Aging↗
PubMed2001

Effect of procyanidolic oligomers on the permeability of the blood-brain barrier.

Blood-brain barrier (BBB) is the site of regulatory mechanisms which control the exchange of substances between the brain and the blood through the wall of 'true' brain capillaries with tight junctions between endothelial cells. In some pathological situations the permeability of the BBB is increased because of a partial proteolytic degradation of some constituents of the capillary basement lamina. In such cases it is important to restore normal permeability. The effect of procyanidolic oligomers (PCO) on the BBB was investigated in vivo with quantitative morphologic procedures. We also investigated the action of this drug on collagen and basement lamina constituents (Matrigel) in vitro. Collagenase injected in lateral brain ventricles was shown to increase BBB permeability. Per os administration of PCO to rats greatly increased the resistance of brain capillaries to bacterial collagenase, as shown by the inhibition of the diffusion of fluorescein-isothiocyanate-marked dextran particles from the blood-stream into the brain tissues. Calf skin collagen pretreated in vitro with PCO became more resistant to the hydrolytic action of collagenase. Similar, even more intense protective effect was seen when basal lamina constituents containing type IV collagen was incubated with PCO before exposure to pronase. These in vitro effects may partly explain the in vivo protective effect of PCO against the alteration of brain capillaries by i.v. injected bacterial collagenase.

Animals↗